[RFC PATCH 0/7] Huge page-table entries for TTM

[RFC PATCH 0/7] Huge page-table entries for TTM

[Thomas Hellström (VMware)]

In order to save TLB space and CPU usage this patchset enables huge- and giant
page-table entries for TTM and TTM-enabled graphics drivers.

Patch 1 introduces a vma_is_special_huge() function to make the mm code
take the same path as DAX when splitting huge- and giant page table entries,
(which is zapping the page-table entry and rely on re-faulting).

Patch 2 makes the mm code split existing huge page-table entries
on huge_fault fallbacks. Typically on COW or on buffer-objects that want
write-notify. COW and write-notification is always done on the lowest
page-table level. See the patch log message for additional considerations.

Patch 3 introduces functions to allow the graphics drivers to manipulate
the caching- and encryption flags of huge page-table entries without ugly
hacks.

Patch 4 implements the huge_fault handler in TTM.

This enables huge page-table entries, provided that the kernel is configured
to support transhuge pages, either by default or using madvise().
However, they are unlikely to be inserted unless the kernel buffer object
pfns and user-space addresses align perfectly. There are various options
here, but since buffer objects that reside in system pages typically start
at huge page boundaries if they are backed by huge pages, we try to enforce
buffer object starting pfns and user-space addresses to be huge page-size
aligned if their size exceeds a huge page-size. If pud-size transhuge
("giant") pages are enabled by the arch, the same holds for those.

Patch 5 implements a drm helper to align user-space addresses according
to the above scheme, if possible.

Patch 6 implements a TTM range manager that does the same for graphics IO
memory.

Patch 7 finally hooks up the helpers of patch 5 and 6 to the vmwgfx driver.
A similar change is needed for graphics drivers that wants a reasonable
likelyhood of actually using huge page-table entries.

Finally, if a buffer object size is not huge-page or giant-page aligned,
its size will NOT be inflated by this patchset. This means that the buffer
object tail will use smaller size page-table entries and thus no memory
overhead occurs. Drivers that want to pay the memory overhead price need to
implement their own scheme to inflate buffer-object sizes.

PMD size huge page-table-entries have been tested with vmwgfx and found to
work well both with system memory backed and IO memory backed buffer objects.

PUD size giant page-table-entries have seen limited (fault and COW) testing
using a modified kernel and a fake vmwgfx TTM memory type. The vmwgfx driver
does otherwise not support 1GB-size IO memory resources.

Comments and suggestions welcome.
Thomas


Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>

[RFC PATCH 1/7] mm: Introduce vma_is_special_huge

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

For VM_PFNMAP and VM_MIXEDMAP vmas that want to support transhuge pages
and -page table entries, introduce vma_is_special_huge() that takes the
same codepaths as vma_is_dax().

The use of "special" follows the definition in memory.c, vm_normal_page():
"Special" mappings do not wish to be associated with a "struct page"
(either it doesn't exist, or it exists but they don't want to touch it)

For PAGE_SIZE pages, "special" is determined per page table entry to be
able to deal with COW pages. But since we don't have huge COW pages,
we can classify a vma as either "special huge" or "normal huge".

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 include/linux/mm.h | 6 ++++++
 mm/huge_memory.c   | 6 +++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 29575d3c1e47..1ee45ef306d8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2838,6 +2838,12 @@ extern long copy_huge_page_from_user(struct page *dst_page,
 				const void __user *usr_src,
 				unsigned int pages_per_huge_page,
 				bool allow_pagefault);
+static inline bool vma_is_special_huge(struct vm_area_struct *vma)
+{
+	return vma_is_dax(vma) || (vma->vm_file &&
+				   (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)));
+}
+
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 13cc93785006..3c83467f09b2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1789,7 +1789,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
 			tlb->fullmm);
 	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
-	if (vma_is_dax(vma)) {
+	if (vma_is_special_huge(vma)) {
 		if (arch_needs_pgtable_deposit())
 			zap_deposited_table(tlb->mm, pmd);
 		spin_unlock(ptl);
@@ -2053,7 +2053,7 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	 */
 	pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
 	tlb_remove_pud_tlb_entry(tlb, pud, addr);
-	if (vma_is_dax(vma)) {
+	if (vma_is_special_huge(vma)) {
 		spin_unlock(ptl);
 		/* No zero page support yet */
 	} else {
@@ -2162,7 +2162,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 		 */
 		if (arch_needs_pgtable_deposit())
 			zap_deposited_table(mm, pmd);
-		if (vma_is_dax(vma))
+		if (vma_is_special_huge(vma))
 			return;
 		page = pmd_page(_pmd);
 		if (!PageDirty(page) && pmd_dirty(_pmd))
-- 
2.21.0

[RFC PATCH 2/7] mm: Split huge pages on write-notify or COW

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

We currently only do COW and write-notify on the PTE level, so if the
huge_fault() handler returns VM_FAULT_FALLBACK on wp faults,
split the huge pages and page-table entries. Also do this for huge PUDs
if there is no huge_fault() handler and the vma is not anonymous, similar
to how it's done for PMDs.

Note that fs/dax.c does the splitting in the huge_fault() handler, but as
huge_fault() is implemented by modules we need to consider whether to
export the splitting functions for use in the modules or whether to try
to keep calls in the core. Opt for the latter. A follow-up patch can
remove the dax.c split_huge_pmd() if needed.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 mm/memory.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 28f162e28144..89b8a7730d66 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3755,11 +3755,14 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
 {
 	if (vma_is_anonymous(vmf->vma))
 		return do_huge_pmd_wp_page(vmf, orig_pmd);
-	if (vmf->vma->vm_ops->huge_fault)
-		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
+	if (vmf->vma->vm_ops->huge_fault) {
+		vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
 
-	/* COW handled on pte level: split pmd */
-	VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
+		if (!(ret & VM_FAULT_FALLBACK))
+			return ret;
+	}
+
+	/* COW or write-notify handled on pte level: split pmd. */
 	__split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
 
 	return VM_FAULT_FALLBACK;
@@ -3787,9 +3790,16 @@ static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	/* No support for anonymous transparent PUD pages yet */
 	if (vma_is_anonymous(vmf->vma))
-		return VM_FAULT_FALLBACK;
-	if (vmf->vma->vm_ops->huge_fault)
-		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
+		goto split;
+	if (vmf->vma->vm_ops->huge_fault) {
+		vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
+
+		if (!(ret & VM_FAULT_FALLBACK))
+			return ret;
+	}
+split:
+	/* COW or write-notify not handled on PUD level: split pud.*/
+	__split_huge_pud(vmf->vma, vmf->pud, vmf->address);
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 	return VM_FAULT_FALLBACK;
 }
-- 
2.21.0

[RFC PATCH 3/7] mm: Add vmf_insert_pfn_xxx_prot() for huge page-table entries

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

For graphics drivers needing to modify the page-protection, add
huge page-table entries counterparts to vmf_insert_prn_prot().

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 include/linux/huge_mm.h | 17 +++++++++++++++--
 mm/huge_memory.c        | 12 ++++++------
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 93d5cf0bc716..f53507203b5e 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -47,8 +47,21 @@ extern bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 			unsigned long addr, pgprot_t newprot,
 			int prot_numa);
-vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write);
-vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write);
+vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
+				   pgprot_t pgprot, bool write);
+static inline vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn,
+					    bool write)
+{
+	return vmf_insert_pfn_pmd_prot(vmf, pfn, vmf->vma->vm_page_prot, write);
+}
+vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
+				   pgprot_t pgprot, bool write);
+static inline vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn,
+					    bool write)
+{
+	return vmf_insert_pfn_pud_prot(vmf, pfn, vmf->vma->vm_page_prot, write);
+}
+
 enum transparent_hugepage_flag {
 	TRANSPARENT_HUGEPAGE_FLAG,
 	TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3c83467f09b2..bbc6b1aa040a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -811,11 +811,11 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 		pte_free(mm, pgtable);
 }
 
-vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
+vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
+				   pgprot_t pgprot, bool write)
 {
 	unsigned long addr = vmf->address & PMD_MASK;
 	struct vm_area_struct *vma = vmf->vma;
-	pgprot_t pgprot = vma->vm_page_prot;
 	pgtable_t pgtable = NULL;
 
 	/*
@@ -843,7 +843,7 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
 	insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
 	return VM_FAULT_NOPAGE;
 }
-EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
+EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
 
 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
@@ -889,11 +889,11 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 	spin_unlock(ptl);
 }
 
-vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
+vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
+				   pgprot_t pgprot, bool write)
 {
 	unsigned long addr = vmf->address & PUD_MASK;
 	struct vm_area_struct *vma = vmf->vma;
-	pgprot_t pgprot = vma->vm_page_prot;
 
 	/*
 	 * If we had pud_special, we could avoid all these restrictions,
@@ -914,7 +914,7 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
 	insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
 	return VM_FAULT_NOPAGE;
 }
-EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
+EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 
 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
-- 
2.21.0

[RFC PATCH 4/7] drm/ttm: Support huge pagefaults

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

Support huge (PMD-size and PUD-size) page-table entries by providing a
huge_fault() callback.
We still support private mappings and write-notify by splitting the huge
page-table entries on write-access.

Note that for huge page-faults to occur, either the kernel needs to be
compiled with trans-huge-pages always enabled, or the kernel needs to be
compiled with trans-huge-pages enabled using madvise, and the user-space
app needs to call madvise() to enable trans-huge pages on a per-mapping
basis.

Furthermore huge page-faults will not occur unless buffer objects and
user-space addresses are aligned on huge page size boundaries.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/ttm/ttm_bo_vm.c | 139 +++++++++++++++++++++++++++++++-
 include/drm/ttm/ttm_bo_api.h    |   3 +-
 2 files changed, 138 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 2098f8d4dfc5..8d6089880e39 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -150,6 +150,84 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
 }
 EXPORT_SYMBOL(ttm_bo_vm_reserve);
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/**
+ * ttm_bo_vm_insert_huge - Insert a pfn for PUD or PMD faults
+ * @vmf: Fault data
+ * @bo: The buffer object
+ * @page_offset: Page offset from bo start
+ * @fault_page_size: The size of the fault in pages.
+ * @pgprot: The page protections.
+ * Does additional checking whether it's possible to insert a PUD or PMD
+ * pfn and performs the insertion.
+ *
+ * Return: VM_FAULT_NOPAGE on successful insertion, VM_FAULT_FALLBACK if
+ * a huge fault was not possible, and a VM_FAULT_ERROR code otherwise.
+ */
+static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
+					struct ttm_buffer_object *bo,
+					pgoff_t page_offset,
+					pgoff_t fault_page_size,
+					pgprot_t pgprot)
+{
+	pgoff_t i;
+	vm_fault_t ret;
+	unsigned long pfn;
+	pfn_t pfnt;
+	struct ttm_tt *ttm = bo->ttm;
+	bool write = vmf->flags & FAULT_FLAG_WRITE;
+
+
+	/* Fault should not cross bo boundary */
+	page_offset &= ~(fault_page_size - 1);
+	if (page_offset + fault_page_size > bo->num_pages)
+		goto out_fallback;
+
+	if (bo->mem.bus.is_iomem)
+		pfn = ttm_bo_io_mem_pfn(bo, page_offset);
+	else
+		pfn = page_to_pfn(ttm->pages[page_offset]);
+
+	/* pfn must be fault_page_size aligned. */
+	if ((pfn & (fault_page_size - 1)) != 0)
+		goto out_fallback;
+
+	/* IO memory is OK now, TT memory must be contigous. */
+	if (!bo->mem.bus.is_iomem)
+		for (i = 1; i < fault_page_size; ++i) {
+			if (page_to_pfn(ttm->pages[page_offset + i]) != pfn + i)
+				goto out_fallback;
+		}
+
+	pfnt = __pfn_to_pfn_t(pfn, PFN_DEV);
+	if (fault_page_size == (HPAGE_PMD_SIZE >> PAGE_SHIFT))
+		ret = vmf_insert_pfn_pmd_prot(vmf, pfnt, pgprot, write);
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+	else if (fault_page_size == (HPAGE_PUD_SIZE >> PAGE_SHIFT))
+		ret = vmf_insert_pfn_pud_prot(vmf, pfnt, pgprot, write);
+#endif
+	else
+		WARN_ON_ONCE(ret = VM_FAULT_FALLBACK);
+
+	if (ret != VM_FAULT_NOPAGE)
+		goto out_fallback;
+
+	return VM_FAULT_NOPAGE;
+out_fallback:
+	count_vm_event(THP_FAULT_FALLBACK);
+	return VM_FAULT_FALLBACK;
+}
+#else
+static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
+					struct ttm_buffer_object *bo,
+					pgoff_t page_offset,
+					pgoff_t fault_page_size,
+					pgprot_t pgprot)
+{
+	return VM_FAULT_NOPAGE;
+}
+#endif
+
 /**
  * ttm_bo_vm_fault_reserved - TTM fault helper
  * @vmf: The struct vm_fault given as argument to the fault callback
@@ -170,7 +248,8 @@ EXPORT_SYMBOL(ttm_bo_vm_reserve);
  */
 vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 				    pgprot_t prot,
-				    pgoff_t num_prefault)
+				    pgoff_t num_prefault,
+				    pgoff_t fault_page_size)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct ttm_buffer_object *bo = vma->vm_private_data;
@@ -262,6 +341,13 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 		prot = pgprot_decrypted(prot);
 	}
 
+	/* We don't prefault on huge faults. Yet. */
+	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && fault_page_size != 1) {
+		ret = ttm_bo_vm_insert_huge(vmf, bo, page_offset,
+					    fault_page_size, prot);
+		goto out_io_unlock;
+	}
+
 	/*
 	 * Speculatively prefault a number of pages. Only error on
 	 * first page.
@@ -320,7 +406,7 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
 		return ret;
 
 	prot = vma->vm_page_prot;
-	ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
+	ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
 	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
 		return ret;
 
@@ -330,6 +416,50 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
 }
 EXPORT_SYMBOL(ttm_bo_vm_fault);
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static vm_fault_t ttm_bo_vm_huge_fault(struct vm_fault *vmf,
+				       enum page_entry_size pe_size)
+{
+	struct vm_area_struct *vma = vmf->vma;
+	pgprot_t prot;
+	struct ttm_buffer_object *bo = vma->vm_private_data;
+	vm_fault_t ret;
+	pgoff_t fault_page_size = 0;
+	bool write = vmf->flags & FAULT_FLAG_WRITE;
+
+	switch (pe_size) {
+	case PE_SIZE_PMD:
+		fault_page_size = HPAGE_PMD_SIZE >> PAGE_SHIFT;
+		break;
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+	case PE_SIZE_PUD:
+		fault_page_size = HPAGE_PUD_SIZE >> PAGE_SHIFT;
+		break;
+#endif
+	default:
+		WARN_ON_ONCE(1);
+		return VM_FAULT_FALLBACK;
+	}
+
+	/* Fallback on write dirty-tracking or COW */
+	if (write && !(pgprot_val(vmf->vma->vm_page_prot) & _PAGE_RW))
+		return VM_FAULT_FALLBACK;
+
+	ret = ttm_bo_vm_reserve(bo, vmf);
+	if (ret)
+		return ret;
+
+	prot = vm_get_page_prot(vma->vm_flags);
+	ret = ttm_bo_vm_fault_reserved(vmf, prot, 1, fault_page_size);
+	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
+		return ret;
+
+	dma_resv_unlock(bo->base.resv);
+
+	return ret;
+}
+#endif
+
 void ttm_bo_vm_open(struct vm_area_struct *vma)
 {
 	struct ttm_buffer_object *bo = vma->vm_private_data;
@@ -431,7 +561,10 @@ static const struct vm_operations_struct ttm_bo_vm_ops = {
 	.fault = ttm_bo_vm_fault,
 	.open = ttm_bo_vm_open,
 	.close = ttm_bo_vm_close,
-	.access = ttm_bo_vm_access
+	.access = ttm_bo_vm_access,
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	.huge_fault = ttm_bo_vm_huge_fault,
+#endif
 };
 
 static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 66ca49db9633..4fc90d53aa15 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -732,7 +732,8 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
 
 vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 				    pgprot_t prot,
-				    pgoff_t num_prefault);
+				    pgoff_t num_prefault,
+				    pgoff_t fault_page_size);
 
 vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf);
 
-- 
2.21.0

[RFC PATCH 5/7] drm: Add a drm_get_unmapped_area() helper

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

This helper is used to align user-space buffer object addresses to
huge page boundaries, minimizing the chance of alignment mismatch
between user-space addresses and physical addresses.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/drm_file.c | 130 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_file.h     |   5 ++
 2 files changed, 135 insertions(+)

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index ea34bc991858..e5b4024cd397 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -31,6 +31,8 @@
  * OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <uapi/asm/mman.h>
+
 #include <linux/dma-fence.h>
 #include <linux/module.h>
 #include <linux/pci.h>
@@ -41,6 +43,7 @@
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
 #include <drm/drm_print.h>
+#include <drm/drm_vma_manager.h>
 
 #include "drm_crtc_internal.h"
 #include "drm_internal.h"
@@ -754,3 +757,130 @@ void drm_send_event(struct drm_device *dev, struct drm_pending_event *e)
 	spin_unlock_irqrestore(&dev->event_lock, irqflags);
 }
 EXPORT_SYMBOL(drm_send_event);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/*
+ * drm_addr_inflate() attempts to construct an aligned area by inflating
+ * the area size and skipping the unaligned start of the area.
+ * adapted from shmem_get_unmapped_area()
+ */
+static unsigned long drm_addr_inflate(unsigned long addr,
+				      unsigned long len,
+				      unsigned long pgoff,
+				      unsigned long flags,
+				      unsigned long huge_size)
+{
+	unsigned long offset, inflated_len;
+	unsigned long inflated_addr;
+	unsigned long inflated_offset;
+
+	offset = (pgoff << PAGE_SHIFT) & (huge_size - 1);
+	if (offset && offset + len < 2 * huge_size)
+		return addr;
+	if ((addr & (huge_size - 1)) == offset)
+		return addr;
+
+	inflated_len = len + huge_size - PAGE_SIZE;
+	if (inflated_len > TASK_SIZE)
+		return addr;
+	if (inflated_len < len)
+		return addr;
+
+	inflated_addr = current->mm->get_unmapped_area(NULL, 0, inflated_len,
+						       0, flags);
+	if (IS_ERR_VALUE(inflated_addr))
+		return addr;
+	if (inflated_addr & ~PAGE_MASK)
+		return addr;
+
+	inflated_offset = inflated_addr & (huge_size - 1);
+	inflated_addr += offset - inflated_offset;
+	if (inflated_offset > offset)
+		inflated_addr += huge_size;
+
+	if (inflated_addr > TASK_SIZE - len)
+		return addr;
+
+	return inflated_addr;
+}
+
+/**
+ * drm_get_unmapped_area() - Get an unused user-space virtual memory area
+ * suitable for huge page table entries.
+ * @file: The struct file representing the address space being mmap()'d.
+ * @uaddr: Start address suggested by user-space.
+ * @len: Length of the area.
+ * @pgoff: The page offset into the address space.
+ * @flags: mmap flags
+ * @mgr: The address space manager used by the drm driver. This argument can
+ * probably be removed at some point when all drivers use the same
+ * address space manager.
+ *
+ * This function attempts to find an unused user-space virtual memory area
+ * that can accommodate the size we want to map, and that is properly
+ * aligned to facilitate huge page table entries matching actual
+ * huge pages or huge page aligned memory in buffer objects. Buffer objects
+ * are assumed to start at huge page boundary pfns (io memory) or be
+ * populated by huge pages aligned to the start of the buffer object
+ * (system- or coherent memory). Adapted from shmem_get_unmapped_area.
+ *
+ * Return: aligned user-space address.
+ */
+unsigned long drm_get_unmapped_area(struct file *file,
+				    unsigned long uaddr, unsigned long len,
+				    unsigned long pgoff, unsigned long flags,
+				    struct drm_vma_offset_manager *mgr)
+{
+	unsigned long addr;
+	unsigned long inflated_addr;
+	struct drm_vma_offset_node *node;
+
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
+	/* Adjust mapping offset to be zero at bo start */
+	drm_vma_offset_lock_lookup(mgr);
+	node = drm_vma_offset_lookup_locked(mgr, pgoff, 1);
+	if (node)
+		pgoff -= node->vm_node.start;
+	drm_vma_offset_unlock_lookup(mgr);
+
+	addr = current->mm->get_unmapped_area(file, uaddr, len, pgoff, flags);
+	if (IS_ERR_VALUE(addr))
+		return addr;
+	if (addr & ~PAGE_MASK)
+		return addr;
+	if (addr > TASK_SIZE - len)
+		return addr;
+
+	if (len < HPAGE_PMD_SIZE)
+		return addr;
+	if (flags & MAP_FIXED)
+		return addr;
+	/*
+	 * Our priority is to support MAP_SHARED mapped hugely;
+	 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
+	 * But if caller specified an address hint, respect that as before.
+	 */
+	if (uaddr)
+		return addr;
+
+	inflated_addr = drm_addr_inflate(addr, len, pgoff, flags,
+					 HPAGE_PMD_SIZE);
+
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) &&
+	    len >= HPAGE_PUD_SIZE)
+		inflated_addr = drm_addr_inflate(inflated_addr, len, pgoff,
+						 flags, HPAGE_PUD_SIZE);
+	return inflated_addr;
+}
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+unsigned long drm_get_unmapped_area(struct file *file,
+				    unsigned long uaddr, unsigned long len,
+				    unsigned long pgoff, unsigned long flags,
+				    struct drm_vma_offset_manager *mgr)
+{
+	return current->mm->get_unmapped_area(file, uaddr, len, pgoff, flags);
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+EXPORT_SYMBOL_GPL(drm_get_unmapped_area);
diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
index 67af60bb527a..4719cc80d547 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -386,5 +386,10 @@ void drm_event_cancel_free(struct drm_device *dev,
 			   struct drm_pending_event *p);
 void drm_send_event_locked(struct drm_device *dev, struct drm_pending_event *e);
 void drm_send_event(struct drm_device *dev, struct drm_pending_event *e);
+struct drm_vma_offset_manager;
+unsigned long drm_get_unmapped_area(struct file *file,
+				    unsigned long uaddr, unsigned long len,
+				    unsigned long pgoff, unsigned long flags,
+				    struct drm_vma_offset_manager *mgr);
 
 #endif /* _DRM_FILE_H_ */
-- 
2.21.0

[RFC PATCH 6/7] drm/ttm: Introduce a huge page aligning TTM range manager.

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

Using huge page-table entries require that the start of a buffer object
is huge page size aligned. So introduce a ttm_bo_man_get_node_huge()
function that attempts to accomplish this for allocations that are larger
than the huge page size, and provide a new range-manager instance that
uses that function.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/ttm/ttm_bo_manager.c | 92 ++++++++++++++++++++++++++++
 include/drm/ttm/ttm_bo_driver.h      |  1 +
 2 files changed, 93 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c b/drivers/gpu/drm/ttm/ttm_bo_manager.c
index 18d3debcc949..26aa1a2ae7f1 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
@@ -89,6 +89,89 @@ static int ttm_bo_man_get_node(struct ttm_mem_type_manager *man,
 	return 0;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static int ttm_bo_insert_aligned(struct drm_mm *mm, struct drm_mm_node *node,
+				 unsigned long align_pages,
+				 const struct ttm_place *place,
+				 struct ttm_mem_reg *mem,
+				 unsigned long lpfn,
+				 enum drm_mm_insert_mode mode)
+{
+	if (align_pages >= mem->page_alignment &&
+	    (!mem->page_alignment || align_pages % mem->page_alignment == 0)) {
+		return drm_mm_insert_node_in_range(mm, node,
+						   mem->num_pages,
+						   align_pages, 0,
+						   place->fpfn, lpfn, mode);
+	}
+
+	return -ENOSPC;
+}
+
+static int ttm_bo_man_get_node_huge(struct ttm_mem_type_manager *man,
+				    struct ttm_buffer_object *bo,
+				    const struct ttm_place *place,
+				    struct ttm_mem_reg *mem)
+{
+	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
+	struct drm_mm *mm = &rman->mm;
+	struct drm_mm_node *node;
+	unsigned long align_pages;
+	unsigned long lpfn;
+	enum drm_mm_insert_mode mode = DRM_MM_INSERT_BEST;
+	int ret;
+
+	node = kzalloc(sizeof(*node), GFP_KERNEL);
+	if (!node)
+		return -ENOMEM;
+
+	lpfn = place->lpfn;
+	if (!lpfn)
+		lpfn = man->size;
+
+	mode = DRM_MM_INSERT_BEST;
+	if (place->flags & TTM_PL_FLAG_TOPDOWN)
+		mode = DRM_MM_INSERT_HIGH;
+
+	spin_lock(&rman->lock);
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)) {
+		align_pages = (HPAGE_PUD_SIZE >> PAGE_SHIFT);
+		if (mem->num_pages >= align_pages) {
+			ret = ttm_bo_insert_aligned(mm, node, align_pages,
+						    place, mem, lpfn, mode);
+			if (!ret)
+				goto found_unlock;
+		}
+	}
+
+	align_pages = (HPAGE_PMD_SIZE >> PAGE_SHIFT);
+	if (mem->num_pages >= align_pages) {
+		ret = ttm_bo_insert_aligned(mm, node, align_pages, place, mem,
+					    lpfn, mode);
+		if (!ret)
+			goto found_unlock;
+	}
+
+	ret = drm_mm_insert_node_in_range(mm, node, mem->num_pages,
+					  mem->page_alignment, 0,
+					  place->fpfn, lpfn, mode);
+found_unlock:
+	spin_unlock(&rman->lock);
+
+	if (unlikely(ret)) {
+		kfree(node);
+	} else {
+		mem->mm_node = node;
+		mem->start = node->start;
+	}
+
+	return 0;
+}
+#else
+#define ttm_bo_man_get_node_huge ttm_bo_man_get_node
+#endif
+
+
 static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
 				struct ttm_mem_reg *mem)
 {
@@ -154,3 +237,12 @@ const struct ttm_mem_type_manager_func ttm_bo_manager_func = {
 	.debug = ttm_bo_man_debug
 };
 EXPORT_SYMBOL(ttm_bo_manager_func);
+
+const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func = {
+	.init = ttm_bo_man_init,
+	.takedown = ttm_bo_man_takedown,
+	.get_node = ttm_bo_man_get_node_huge,
+	.put_node = ttm_bo_man_put_node,
+	.debug = ttm_bo_man_debug
+};
+EXPORT_SYMBOL(ttm_bo_manager_huge_func);
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index cac7a8a0825a..868bd0d4be6a 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -888,5 +888,6 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo);
 pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
 
 extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
+extern const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func;
 
 #endif
-- 
2.21.0

[RFC PATCH 7/7] drm/vmwgfx: Hook up the helpers to align buffer objects

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

Start using the helpers that align buffer object user-space addresses and
buffer object vram addresses to huge page boundaries.
This is to improve the chances of allowing huge page-table entries.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.c        | 13 +++++++++++++
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.h        |  1 +
 drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c |  2 +-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index 81a95651643f..ebeaea4b87e9 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -1216,6 +1216,18 @@ static void vmw_remove(struct pci_dev *pdev)
 	drm_put_dev(dev);
 }
 
+static unsigned long
+vmw_get_unmapped_area(struct file *file, unsigned long uaddr,
+		      unsigned long len, unsigned long pgoff,
+		      unsigned long flags)
+{
+	struct drm_file *file_priv = file->private_data;
+	struct vmw_private *dev_priv = vmw_priv(file_priv->minor->dev);
+
+	return drm_get_unmapped_area(file, uaddr, len, pgoff, flags,
+				     &dev_priv->vma_manager);
+}
+
 static int vmwgfx_pm_notifier(struct notifier_block *nb, unsigned long val,
 			      void *ptr)
 {
@@ -1387,6 +1399,7 @@ static const struct file_operations vmwgfx_driver_fops = {
 	.compat_ioctl = vmw_compat_ioctl,
 #endif
 	.llseek = noop_llseek,
+	.get_unmapped_area = vmw_get_unmapped_area,
 };
 
 static struct drm_driver driver = {
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index b18842f73081..7232e912dbc0 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -918,6 +918,7 @@ extern int vmw_mmap(struct file *filp, struct vm_area_struct *vma);
 
 extern void vmw_validation_mem_init_ttm(struct vmw_private *dev_priv,
 					size_t gran);
+
 /**
  * TTM buffer object driver - vmwgfx_ttm_buffer.c
  */
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
index d8ea3dd10af0..c319fe0ca912 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
@@ -754,7 +754,7 @@ static int vmw_init_mem_type(struct ttm_bo_device *bdev, uint32_t type,
 		break;
 	case TTM_PL_VRAM:
 		/* "On-card" video ram */
-		man->func = &ttm_bo_manager_func;
+		man->func = &ttm_bo_manager_huge_func;
 		man->gpu_offset = 0;
 		man->flags = TTM_MEMTYPE_FLAG_FIXED | TTM_MEMTYPE_FLAG_MAPPABLE;
 		man->available_caching = TTM_PL_FLAG_CACHED;
-- 
2.21.0

Re: [RFC PATCH 4/7] drm/ttm: Support huge pagefaults

[Christian König]

Am 27.11.19 um 09:31 schrieb Thomas Hellström (VMware):
> From: Thomas Hellstrom <thellstrom@vmware.com>
>
> Support huge (PMD-size and PUD-size) page-table entries by providing a
> huge_fault() callback.
> We still support private mappings and write-notify by splitting the huge
> page-table entries on write-access.
>
> Note that for huge page-faults to occur, either the kernel needs to be
> compiled with trans-huge-pages always enabled, or the kernel needs to be
> compiled with trans-huge-pages enabled using madvise, and the user-space
> app needs to call madvise() to enable trans-huge pages on a per-mapping
> basis.
>
> Furthermore huge page-faults will not occur unless buffer objects and
> user-space addresses are aligned on huge page size boundaries.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: "Jérôme Glisse" <jglisse@redhat.com>
> Cc: "Christian König" <christian.koenig@amd.com>
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_vm.c | 139 +++++++++++++++++++++++++++++++-
>   include/drm/ttm/ttm_bo_api.h    |   3 +-
>   2 files changed, 138 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 2098f8d4dfc5..8d6089880e39 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -150,6 +150,84 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
>   }
>   EXPORT_SYMBOL(ttm_bo_vm_reserve);
>   
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +/**
> + * ttm_bo_vm_insert_huge - Insert a pfn for PUD or PMD faults
> + * @vmf: Fault data
> + * @bo: The buffer object
> + * @page_offset: Page offset from bo start
> + * @fault_page_size: The size of the fault in pages.
> + * @pgprot: The page protections.
> + * Does additional checking whether it's possible to insert a PUD or PMD
> + * pfn and performs the insertion.
> + *
> + * Return: VM_FAULT_NOPAGE on successful insertion, VM_FAULT_FALLBACK if
> + * a huge fault was not possible, and a VM_FAULT_ERROR code otherwise.
> + */
> +static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
> +					struct ttm_buffer_object *bo,
> +					pgoff_t page_offset,
> +					pgoff_t fault_page_size,
> +					pgprot_t pgprot)
> +{
> +	pgoff_t i;
> +	vm_fault_t ret;
> +	unsigned long pfn;
> +	pfn_t pfnt;
> +	struct ttm_tt *ttm = bo->ttm;
> +	bool write = vmf->flags & FAULT_FLAG_WRITE;
> +
> +
> +	/* Fault should not cross bo boundary */
> +	page_offset &= ~(fault_page_size - 1);
> +	if (page_offset + fault_page_size > bo->num_pages)
> +		goto out_fallback;
> +
> +	if (bo->mem.bus.is_iomem)
> +		pfn = ttm_bo_io_mem_pfn(bo, page_offset);
> +	else
> +		pfn = page_to_pfn(ttm->pages[page_offset]);
> +
> +	/* pfn must be fault_page_size aligned. */
> +	if ((pfn & (fault_page_size - 1)) != 0)
> +		goto out_fallback;
> +
> +	/* IO memory is OK now, TT memory must be contigous. */

That won't work correctly, IO mem might not be contiguous either.

We either need to call ttm_bo_io_mem_pfn() multiple times and check that 
the addresses are linear or return the length additional to the pfn.

Regards,
Christian.

> +	if (!bo->mem.bus.is_iomem)
> +		for (i = 1; i < fault_page_size; ++i) {
> +			if (page_to_pfn(ttm->pages[page_offset + i]) != pfn + i)
> +				goto out_fallback;
> +		}
> +
> +	pfnt = __pfn_to_pfn_t(pfn, PFN_DEV);
> +	if (fault_page_size == (HPAGE_PMD_SIZE >> PAGE_SHIFT))
> +		ret = vmf_insert_pfn_pmd_prot(vmf, pfnt, pgprot, write);
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> +	else if (fault_page_size == (HPAGE_PUD_SIZE >> PAGE_SHIFT))
> +		ret = vmf_insert_pfn_pud_prot(vmf, pfnt, pgprot, write);
> +#endif
> +	else
> +		WARN_ON_ONCE(ret = VM_FAULT_FALLBACK);
> +
> +	if (ret != VM_FAULT_NOPAGE)
> +		goto out_fallback;
> +
> +	return VM_FAULT_NOPAGE;
> +out_fallback:
> +	count_vm_event(THP_FAULT_FALLBACK);
> +	return VM_FAULT_FALLBACK;
> +}
> +#else
> +static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
> +					struct ttm_buffer_object *bo,
> +					pgoff_t page_offset,
> +					pgoff_t fault_page_size,
> +					pgprot_t pgprot)
> +{
> +	return VM_FAULT_NOPAGE;
> +}
> +#endif
> +
>   /**
>    * ttm_bo_vm_fault_reserved - TTM fault helper
>    * @vmf: The struct vm_fault given as argument to the fault callback
> @@ -170,7 +248,8 @@ EXPORT_SYMBOL(ttm_bo_vm_reserve);
>    */
>   vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
>   				    pgprot_t prot,
> -				    pgoff_t num_prefault)
> +				    pgoff_t num_prefault,
> +				    pgoff_t fault_page_size)
>   {
>   	struct vm_area_struct *vma = vmf->vma;
>   	struct ttm_buffer_object *bo = vma->vm_private_data;
> @@ -262,6 +341,13 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
>   		prot = pgprot_decrypted(prot);
>   	}
>   
> +	/* We don't prefault on huge faults. Yet. */
> +	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && fault_page_size != 1) {
> +		ret = ttm_bo_vm_insert_huge(vmf, bo, page_offset,
> +					    fault_page_size, prot);
> +		goto out_io_unlock;
> +	}
> +
>   	/*
>   	 * Speculatively prefault a number of pages. Only error on
>   	 * first page.
> @@ -320,7 +406,7 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
>   		return ret;
>   
>   	prot = vma->vm_page_prot;
> -	ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
> +	ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
>   	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
>   		return ret;
>   
> @@ -330,6 +416,50 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
>   }
>   EXPORT_SYMBOL(ttm_bo_vm_fault);
>   
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +static vm_fault_t ttm_bo_vm_huge_fault(struct vm_fault *vmf,
> +				       enum page_entry_size pe_size)
> +{
> +	struct vm_area_struct *vma = vmf->vma;
> +	pgprot_t prot;
> +	struct ttm_buffer_object *bo = vma->vm_private_data;
> +	vm_fault_t ret;
> +	pgoff_t fault_page_size = 0;
> +	bool write = vmf->flags & FAULT_FLAG_WRITE;
> +
> +	switch (pe_size) {
> +	case PE_SIZE_PMD:
> +		fault_page_size = HPAGE_PMD_SIZE >> PAGE_SHIFT;
> +		break;
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> +	case PE_SIZE_PUD:
> +		fault_page_size = HPAGE_PUD_SIZE >> PAGE_SHIFT;
> +		break;
> +#endif
> +	default:
> +		WARN_ON_ONCE(1);
> +		return VM_FAULT_FALLBACK;
> +	}
> +
> +	/* Fallback on write dirty-tracking or COW */
> +	if (write && !(pgprot_val(vmf->vma->vm_page_prot) & _PAGE_RW))
> +		return VM_FAULT_FALLBACK;
> +
> +	ret = ttm_bo_vm_reserve(bo, vmf);
> +	if (ret)
> +		return ret;
> +
> +	prot = vm_get_page_prot(vma->vm_flags);
> +	ret = ttm_bo_vm_fault_reserved(vmf, prot, 1, fault_page_size);
> +	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
> +		return ret;
> +
> +	dma_resv_unlock(bo->base.resv);
> +
> +	return ret;
> +}
> +#endif
> +
>   void ttm_bo_vm_open(struct vm_area_struct *vma)
>   {
>   	struct ttm_buffer_object *bo = vma->vm_private_data;
> @@ -431,7 +561,10 @@ static const struct vm_operations_struct ttm_bo_vm_ops = {
>   	.fault = ttm_bo_vm_fault,
>   	.open = ttm_bo_vm_open,
>   	.close = ttm_bo_vm_close,
> -	.access = ttm_bo_vm_access
> +	.access = ttm_bo_vm_access,
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +	.huge_fault = ttm_bo_vm_huge_fault,
> +#endif
>   };
>   
>   static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 66ca49db9633..4fc90d53aa15 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -732,7 +732,8 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
>   
>   vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
>   				    pgprot_t prot,
> -				    pgoff_t num_prefault);
> +				    pgoff_t num_prefault,
> +				    pgoff_t fault_page_size);
>   
>   vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf);
>   

Re: [RFC PATCH 6/7] drm/ttm: Introduce a huge page aligning TTM range manager.

[Christian König]

I don't see the advantage over just increasing the alignment 
requirements in the driver side?

That would be a one liner if I'm not completely mistaken.

Regards,
Christian.

Am 27.11.19 um 09:31 schrieb Thomas Hellström (VMware):
> From: Thomas Hellstrom <thellstrom@vmware.com>
>
> Using huge page-table entries require that the start of a buffer object
> is huge page size aligned. So introduce a ttm_bo_man_get_node_huge()
> function that attempts to accomplish this for allocations that are larger
> than the huge page size, and provide a new range-manager instance that
> uses that function.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: "Jérôme Glisse" <jglisse@redhat.com>
> Cc: "Christian König" <christian.koenig@amd.com>
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_manager.c | 92 ++++++++++++++++++++++++++++
>   include/drm/ttm/ttm_bo_driver.h      |  1 +
>   2 files changed, 93 insertions(+)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c b/drivers/gpu/drm/ttm/ttm_bo_manager.c
> index 18d3debcc949..26aa1a2ae7f1 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
> @@ -89,6 +89,89 @@ static int ttm_bo_man_get_node(struct ttm_mem_type_manager *man,
>   	return 0;
>   }
>   
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +static int ttm_bo_insert_aligned(struct drm_mm *mm, struct drm_mm_node *node,
> +				 unsigned long align_pages,
> +				 const struct ttm_place *place,
> +				 struct ttm_mem_reg *mem,
> +				 unsigned long lpfn,
> +				 enum drm_mm_insert_mode mode)
> +{
> +	if (align_pages >= mem->page_alignment &&
> +	    (!mem->page_alignment || align_pages % mem->page_alignment == 0)) {
> +		return drm_mm_insert_node_in_range(mm, node,
> +						   mem->num_pages,
> +						   align_pages, 0,
> +						   place->fpfn, lpfn, mode);
> +	}
> +
> +	return -ENOSPC;
> +}
> +
> +static int ttm_bo_man_get_node_huge(struct ttm_mem_type_manager *man,
> +				    struct ttm_buffer_object *bo,
> +				    const struct ttm_place *place,
> +				    struct ttm_mem_reg *mem)
> +{
> +	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
> +	struct drm_mm *mm = &rman->mm;
> +	struct drm_mm_node *node;
> +	unsigned long align_pages;
> +	unsigned long lpfn;
> +	enum drm_mm_insert_mode mode = DRM_MM_INSERT_BEST;
> +	int ret;
> +
> +	node = kzalloc(sizeof(*node), GFP_KERNEL);
> +	if (!node)
> +		return -ENOMEM;
> +
> +	lpfn = place->lpfn;
> +	if (!lpfn)
> +		lpfn = man->size;
> +
> +	mode = DRM_MM_INSERT_BEST;
> +	if (place->flags & TTM_PL_FLAG_TOPDOWN)
> +		mode = DRM_MM_INSERT_HIGH;
> +
> +	spin_lock(&rman->lock);
> +	if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)) {
> +		align_pages = (HPAGE_PUD_SIZE >> PAGE_SHIFT);
> +		if (mem->num_pages >= align_pages) {
> +			ret = ttm_bo_insert_aligned(mm, node, align_pages,
> +						    place, mem, lpfn, mode);
> +			if (!ret)
> +				goto found_unlock;
> +		}
> +	}
> +
> +	align_pages = (HPAGE_PMD_SIZE >> PAGE_SHIFT);
> +	if (mem->num_pages >= align_pages) {
> +		ret = ttm_bo_insert_aligned(mm, node, align_pages, place, mem,
> +					    lpfn, mode);
> +		if (!ret)
> +			goto found_unlock;
> +	}
> +
> +	ret = drm_mm_insert_node_in_range(mm, node, mem->num_pages,
> +					  mem->page_alignment, 0,
> +					  place->fpfn, lpfn, mode);
> +found_unlock:
> +	spin_unlock(&rman->lock);
> +
> +	if (unlikely(ret)) {
> +		kfree(node);
> +	} else {
> +		mem->mm_node = node;
> +		mem->start = node->start;
> +	}
> +
> +	return 0;
> +}
> +#else
> +#define ttm_bo_man_get_node_huge ttm_bo_man_get_node
> +#endif
> +
> +
>   static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
>   				struct ttm_mem_reg *mem)
>   {
> @@ -154,3 +237,12 @@ const struct ttm_mem_type_manager_func ttm_bo_manager_func = {
>   	.debug = ttm_bo_man_debug
>   };
>   EXPORT_SYMBOL(ttm_bo_manager_func);
> +
> +const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func = {
> +	.init = ttm_bo_man_init,
> +	.takedown = ttm_bo_man_takedown,
> +	.get_node = ttm_bo_man_get_node_huge,
> +	.put_node = ttm_bo_man_put_node,
> +	.debug = ttm_bo_man_debug
> +};
> +EXPORT_SYMBOL(ttm_bo_manager_huge_func);
> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> index cac7a8a0825a..868bd0d4be6a 100644
> --- a/include/drm/ttm/ttm_bo_driver.h
> +++ b/include/drm/ttm/ttm_bo_driver.h
> @@ -888,5 +888,6 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo);
>   pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
>   
>   extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
> +extern const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func;
>   
>   #endif

Re: [RFC PATCH 4/7] drm/ttm: Support huge pagefaults

[Thomas Hellström (VMware)]

On 11/27/19 10:12 AM, Christian König wrote:
> Am 27.11.19 um 09:31 schrieb Thomas Hellström (VMware):
>> From: Thomas Hellstrom <thellstrom@vmware.com>
>>
>> Support huge (PMD-size and PUD-size) page-table entries by providing a
>> huge_fault() callback.
>> We still support private mappings and write-notify by splitting the huge
>> page-table entries on write-access.
>>
>> Note that for huge page-faults to occur, either the kernel needs to be
>> compiled with trans-huge-pages always enabled, or the kernel needs to be
>> compiled with trans-huge-pages enabled using madvise, and the user-space
>> app needs to call madvise() to enable trans-huge pages on a per-mapping
>> basis.
>>
>> Furthermore huge page-faults will not occur unless buffer objects and
>> user-space addresses are aligned on huge page size boundaries.
>>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Michal Hocko <mhocko@suse.com>
>> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>> Cc: Ralph Campbell <rcampbell@nvidia.com>
>> Cc: "Jérôme Glisse" <jglisse@redhat.com>
>> Cc: "Christian König" <christian.koenig@amd.com>
>> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
>> ---
>>   drivers/gpu/drm/ttm/ttm_bo_vm.c | 139 +++++++++++++++++++++++++++++++-
>>   include/drm/ttm/ttm_bo_api.h    |   3 +-
>>   2 files changed, 138 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c 
>> b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>> index 2098f8d4dfc5..8d6089880e39 100644
>> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
>> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>> @@ -150,6 +150,84 @@ vm_fault_t ttm_bo_vm_reserve(struct 
>> ttm_buffer_object *bo,
>>   }
>>   EXPORT_SYMBOL(ttm_bo_vm_reserve);
>>   +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> +/**
>> + * ttm_bo_vm_insert_huge - Insert a pfn for PUD or PMD faults
>> + * @vmf: Fault data
>> + * @bo: The buffer object
>> + * @page_offset: Page offset from bo start
>> + * @fault_page_size: The size of the fault in pages.
>> + * @pgprot: The page protections.
>> + * Does additional checking whether it's possible to insert a PUD or 
>> PMD
>> + * pfn and performs the insertion.
>> + *
>> + * Return: VM_FAULT_NOPAGE on successful insertion, 
>> VM_FAULT_FALLBACK if
>> + * a huge fault was not possible, and a VM_FAULT_ERROR code otherwise.
>> + */
>> +static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
>> +                    struct ttm_buffer_object *bo,
>> +                    pgoff_t page_offset,
>> +                    pgoff_t fault_page_size,
>> +                    pgprot_t pgprot)
>> +{
>> +    pgoff_t i;
>> +    vm_fault_t ret;
>> +    unsigned long pfn;
>> +    pfn_t pfnt;
>> +    struct ttm_tt *ttm = bo->ttm;
>> +    bool write = vmf->flags & FAULT_FLAG_WRITE;
>> +
>> +
>> +    /* Fault should not cross bo boundary */
>> +    page_offset &= ~(fault_page_size - 1);
>> +    if (page_offset + fault_page_size > bo->num_pages)
>> +        goto out_fallback;
>> +
>> +    if (bo->mem.bus.is_iomem)
>> +        pfn = ttm_bo_io_mem_pfn(bo, page_offset);
>> +    else
>> +        pfn = page_to_pfn(ttm->pages[page_offset]);
>> +
>> +    /* pfn must be fault_page_size aligned. */
>> +    if ((pfn & (fault_page_size - 1)) != 0)
>> +        goto out_fallback;
>> +
>> +    /* IO memory is OK now, TT memory must be contigous. */
>
> That won't work correctly, IO mem might not be contiguous either.
>
> We either need to call ttm_bo_io_mem_pfn() multiple times and check 
> that the addresses are linear or return the length additional to the pfn.

Yes, you're right. Will fix that up.

Thanks,

Thomas



>
> Regards,
> Christian. 

Re: [RFC PATCH 6/7] drm/ttm: Introduce a huge page aligning TTM range manager.

[Thomas Hellström (VMware)]

On 11/27/19 11:05 AM, Christian König wrote:
> I don't see the advantage over just increasing the alignment 
> requirements in the driver side?

The advantage is that we don't fail space allocation if we can't match 
the alignment. We instead fall back to a lower alignment if it's 
compatible with the GPU required alignment.

Thanks,
/Thomas


>
> That would be a one liner if I'm not completely mistaken.
>
> Regards,
> Christian.
>
> Am 27.11.19 um 09:31 schrieb Thomas Hellström (VMware):
>> From: Thomas Hellstrom <thellstrom@vmware.com>
>>
>> Using huge page-table entries require that the start of a buffer object
>> is huge page size aligned. So introduce a ttm_bo_man_get_node_huge()
>> function that attempts to accomplish this for allocations that are 
>> larger
>> than the huge page size, and provide a new range-manager instance that
>> uses that function.
>>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Michal Hocko <mhocko@suse.com>
>> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>> Cc: Ralph Campbell <rcampbell@nvidia.com>
>> Cc: "Jérôme Glisse" <jglisse@redhat.com>
>> Cc: "Christian König" <christian.koenig@amd.com>
>> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
>> ---
>>   drivers/gpu/drm/ttm/ttm_bo_manager.c | 92 ++++++++++++++++++++++++++++
>>   include/drm/ttm/ttm_bo_driver.h      |  1 +
>>   2 files changed, 93 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c 
>> b/drivers/gpu/drm/ttm/ttm_bo_manager.c
>> index 18d3debcc949..26aa1a2ae7f1 100644
>> --- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
>> +++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
>> @@ -89,6 +89,89 @@ static int ttm_bo_man_get_node(struct 
>> ttm_mem_type_manager *man,
>>       return 0;
>>   }
>>   +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> +static int ttm_bo_insert_aligned(struct drm_mm *mm, struct 
>> drm_mm_node *node,
>> +                 unsigned long align_pages,
>> +                 const struct ttm_place *place,
>> +                 struct ttm_mem_reg *mem,
>> +                 unsigned long lpfn,
>> +                 enum drm_mm_insert_mode mode)
>> +{
>> +    if (align_pages >= mem->page_alignment &&
>> +        (!mem->page_alignment || align_pages % mem->page_alignment 
>> == 0)) {
>> +        return drm_mm_insert_node_in_range(mm, node,
>> +                           mem->num_pages,
>> +                           align_pages, 0,
>> +                           place->fpfn, lpfn, mode);
>> +    }
>> +
>> +    return -ENOSPC;
>> +}
>> +
>> +static int ttm_bo_man_get_node_huge(struct ttm_mem_type_manager *man,
>> +                    struct ttm_buffer_object *bo,
>> +                    const struct ttm_place *place,
>> +                    struct ttm_mem_reg *mem)
>> +{
>> +    struct ttm_range_manager *rman = (struct ttm_range_manager *) 
>> man->priv;
>> +    struct drm_mm *mm = &rman->mm;
>> +    struct drm_mm_node *node;
>> +    unsigned long align_pages;
>> +    unsigned long lpfn;
>> +    enum drm_mm_insert_mode mode = DRM_MM_INSERT_BEST;
>> +    int ret;
>> +
>> +    node = kzalloc(sizeof(*node), GFP_KERNEL);
>> +    if (!node)
>> +        return -ENOMEM;
>> +
>> +    lpfn = place->lpfn;
>> +    if (!lpfn)
>> +        lpfn = man->size;
>> +
>> +    mode = DRM_MM_INSERT_BEST;
>> +    if (place->flags & TTM_PL_FLAG_TOPDOWN)
>> +        mode = DRM_MM_INSERT_HIGH;
>> +
>> +    spin_lock(&rman->lock);
>> +    if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)) {
>> +        align_pages = (HPAGE_PUD_SIZE >> PAGE_SHIFT);
>> +        if (mem->num_pages >= align_pages) {
>> +            ret = ttm_bo_insert_aligned(mm, node, align_pages,
>> +                            place, mem, lpfn, mode);
>> +            if (!ret)
>> +                goto found_unlock;
>> +        }
>> +    }
>> +
>> +    align_pages = (HPAGE_PMD_SIZE >> PAGE_SHIFT);
>> +    if (mem->num_pages >= align_pages) {
>> +        ret = ttm_bo_insert_aligned(mm, node, align_pages, place, mem,
>> +                        lpfn, mode);
>> +        if (!ret)
>> +            goto found_unlock;
>> +    }
>> +
>> +    ret = drm_mm_insert_node_in_range(mm, node, mem->num_pages,
>> +                      mem->page_alignment, 0,
>> +                      place->fpfn, lpfn, mode);
>> +found_unlock:
>> +    spin_unlock(&rman->lock);
>> +
>> +    if (unlikely(ret)) {
>> +        kfree(node);
>> +    } else {
>> +        mem->mm_node = node;
>> +        mem->start = node->start;
>> +    }
>> +
>> +    return 0;
>> +}
>> +#else
>> +#define ttm_bo_man_get_node_huge ttm_bo_man_get_node
>> +#endif
>> +
>> +
>>   static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
>>                   struct ttm_mem_reg *mem)
>>   {
>> @@ -154,3 +237,12 @@ const struct ttm_mem_type_manager_func 
>> ttm_bo_manager_func = {
>>       .debug = ttm_bo_man_debug
>>   };
>>   EXPORT_SYMBOL(ttm_bo_manager_func);
>> +
>> +const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func = {
>> +    .init = ttm_bo_man_init,
>> +    .takedown = ttm_bo_man_takedown,
>> +    .get_node = ttm_bo_man_get_node_huge,
>> +    .put_node = ttm_bo_man_put_node,
>> +    .debug = ttm_bo_man_debug
>> +};
>> +EXPORT_SYMBOL(ttm_bo_manager_huge_func);
>> diff --git a/include/drm/ttm/ttm_bo_driver.h 
>> b/include/drm/ttm/ttm_bo_driver.h
>> index cac7a8a0825a..868bd0d4be6a 100644
>> --- a/include/drm/ttm/ttm_bo_driver.h
>> +++ b/include/drm/ttm/ttm_bo_driver.h
>> @@ -888,5 +888,6 @@ int ttm_bo_pipeline_gutting(struct 
>> ttm_buffer_object *bo);
>>   pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
>>     extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
>> +extern const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func;
>>     #endif